732 
Jour nal of Agricultural Research 
Vol. XXVIII, No. 8 
Plants common along washes (PI. 2, A) in Coachella Valley may be listed as a 
modification of this same association. The more important plants are: 
Parosela arborescens (Torr.) Heller. 
Chilopsis linearis (Cav.) Sweet. 
Hymenoclea salsola Torr. & Gray. 
Cercidium torreyanum (S. Wats.) Sarg. 
Parosela schottii (Torr.) Heller. 
Asclepias subulata Decne. 
Bebbia juncea aspera Greene. 
Olneya tesota A. Gray. 
Petalonyx thurberi A. Gray. 
Psathyrotes ramosissima (Torr.) Gray. 
Eriogonum thomasii Torr. 
B eloper one californica Benth. 
Lupinus sp. 
Phacelia sp. 
GIANT CACTUS AND PALOVERDE ASSOCIATION 
The low hills surrounding the Gila Valley and the residual soils, which are 
rough and stony, are characterized by the giant cactus and paloverde type of 
vegetation (PI. 2, B). This is similar in general character to the Yucca and cactus 
type in Coachella Valley, though here the appearance is much more striking due, 
on the one hand, to the larger areas, a result of the gradual slope, and, on the other 
hand, to the giant cactus, Carnegiea gigantea (Engelm.) Britton & Bose, which 
stands high above all other plants. The higher rainfall in this region produces a 
much more luxuriant type of desert growth, and it is doubtful if any type of 
vegetation in the United States presents more interesting plants (PL 3, A). 
This association is well developed in the region about Chandler, Ariz. The 
following list gives a good idea of the botanical composition: 
PERENNIAL SPECIES 
Common or Frequent 
Carnegiea gigantea (Engelm.) Britton & 
Rose. 
Cercidium torreyanum (S. Wats.) Sarg. 
Opuntia bigelovii Engelm. 
Ferocactus wislizeni (Engelm.) Brit¬ 
ton & Rose. 
Fouquieria splendens Engelm. 
Encelia farinosa A. Gray . 
Franseria durnosa A. Gray. 
Covillea glutinosa (Engelm.) Rydb. 
Franseria deltoides Torr. 
Eriogonum fasciculatum Benth. 
Olneya tesota A. Gray. 
Less Frequent or Rare 
Simmondsia calif ornica Nutt. Sphaeralcea coulteri A. Gray. 
ANNUAL AND BIENNIAL SPECIES 
Common or Frequent 
Plantago fastigiata Morris. 
Festuca octoflora Walt. 
Thelypodium lasiophyllum (Hook. & 
Arn.) Greene. 
Amsinckia intermedia Fisch. & Mey. 
Pectocarya penicillata (Hook. & Arn.) 
A. DC. 
Tillaestrum aquaticum (L.) Britt. 
Phacelia sp. 
Lepidium lasiocarpum Nutt. 
Conanthus demissus (A. Gray) Heller. 
Baeria aristata (Nutt.) Coville. 
Cryptanthe sp. 
